Performs a binary search for in between start and end. - CSharp System

CSharp examples for System:IComparable

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Description

Performs a binary search for in between start and end.

Demo Code


using System;// ww  w .j  a  va 2  s  .  c  o  m

namespace Utility
{
    namespace Algorithms
    {
        namespace Search
        {
            /// <summary>
            /// Static class containing methods that search for items in sorted arrays.
            /// </summary>
            /// <typeparam name="T">The type of value to search for.</typeparam>
            public static partial class Search<T>
                where T : IComparable<T>
            {
                /// <summary>
                /// Performs a binary search for <paramref name="item"/> in <paramref name="array"/>.
                /// </summary>
                /// <param name="array">The array to search.</param>
                /// <param name="item">The item to search for.</param>
                /// <returns>An integer indicating the index of the largest element that is smaller than or equal to <paramref name="item"/>.</returns>
                public static int BinarySearch(T[] array, T item)
                {
                    return BinarySearch(array, item, -1, array.Length);
                }

                /// <summary>
                /// Performs a binary search for <paramref name="item"/> in <paramref name="array"/> between <paramref name="start"/> and <paramref name="end"/>.
                /// </summary>
                /// <param name="array">The array to search.</param>
                /// <param name="item">The item to search for.</param>
                /// <param name="start">The lowest index to look at.</param>
                /// <param name="end">The highest index to look at.</param>
                /// <returns>An integer indicating the index of the largest element that is smaller than or equal to <paramref name="item"/>.</returns>
                public static int BinarySearch(T[] array, T item, int start, int end)
                {
                    int half;
                    while (end > start + 1)
                    {
                        half = (end + start) / 2;
                        if (array[half].CompareTo(item) <= 0)
                            start = half;
                        else
                            end = half;
                    }
                    return start;
                }
            }
        }
    }
}

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